Conductive Porous MXene for Bionic, Wearable, and Precise Gesture Motion Sensors

Reliable, wide range, and highly sensitive joint movement monitoring is essential for training activities, human behavior analysis, and human-machine interfaces. Yet, most current motion sensors work on the nano/microcracks induced by the tensile deformation on the convex surface of joints during joint movements, which cannot satisfy requirements of ultrawide detectable angle range, high angle sensitivity, conformability, and consistence under cyclic movements. In nature, scorpions sense small vibrations by allowing for compression strain conversion from external mechanical vibrations through crack-shaped slit sensilla. Here, we demonstrated that ultraconformal sensors based on controlled slit structures, inspired by the geometry of a scorpion’s slit sensilla, exhibit high sensitivity (0.45%deg-1), ultralow angle detection threshold (~15°), fast response/relaxation times (115/72 ms), wide range (15° ~120°), and durability (over 1000 cycles). Also, a user-friendly, hybrid sign language system has been developed to realize Chinese and American sign language recognition and feedback through video and speech broadcasts, making these conformal motion sensors promising candidates for joint movement monitoring in wearable electronics and robotics technology.

Development of the Ultralight Hybrid Pneumatic Artificial Muscle: Modelling and optimization

Pneumatic artificial muscles (PAMs) are one of the key technologies in soft robotics, and they enable actuation in mobile robots, in wearable devices and exoskeletons for assistive and rehabilitative purposes. While they recently showed relevant improvements, they still present quite low payload, limited bandwidth, and lack of repeatability, controllability and robustness. Vacuum-based actuation has been recently demonstrated as a very promising solution, and many challenges are still open, like generating at the same time a large contraction ratio, and a high blocking force with enhanced axial stiffness. In this paper, a novel Ultralight Hybrid PAM (UH-PAM), based on bellow-type elastomeric skin and vacuum actuation, is presented. In particular, open-cell foam is exploited as a structural backbone, together with plastic rings, all embedded in a thin skin. The design and optimization combine numerical, analytical, and experimental data. Both static and dynamic analysis are performed. The weight of the optimized actuator is only 20 g. Nevertheless, a contraction ratio up to 50% and a maximum payload of 3 kg can be achieved. From a dynamic point of view, a rise time of 0.5 s for the contraction phase is observed. Although hysteresis is significant when using the whole contraction span, it can be reduced (down to 11.5%) by tuning both the vacuum range and the operating frequency for cyclic movements. Finally, to demonstrate the potentiality of this soft actuation approach, a 3 DoFs Stewart platform is built. The feasibility of performing smooth movements by exploiting open-loop control is shown through simple and more complex handwriting figures projected on the XY plane.

Evaluation of vehicular contact force on bridge joints by vibration responses and object detection

<p>Expansion joints on bridges should accommodate cyclic movements to minimize imposition of secondary stresses in the structure. However, these joints are highly susceptible to severe and repeated vehicular impact that results their inherent discontinuity. In this paper, a portable on- board system including accelerometers and a drive recorder to evaluate the vehicular contact force on bridge joints is proposed. First, from the acceleration responses of the vehicle, the contact force exerted on the road surface is estimated from a half-car model by Kalman Filter. Next, extraction of the expansion joints is performed by object detection from videos taken by the drive recorder. Finally, a relative comparison of the contact forces acting on joints is performed, with location identification on the map. The proposed system benefits to utilize the dynamic contact forces results from on-board system to detect the potential risky joints more precisely and efficiently.</p>

Experimental Study on Flexible Deformation of a Flapping Wing with a Rectangular Planform

A flexible flapping wing with a rectangular planform was designed to investigate the influence of flexible deformation. This planform is more convenient and easier to define and analyzed its deforming properties in the direction of spanwise and chordwise. The flapping wings were created from carbon fiber skeleton and polyester membrane with similar size to medium birds. Their flexibility of deformations was tested using a pair of high-speed cameras, and the 3D deformations were reconstructed using the digital image correlation technology. To obtain the relationship between the flexible deformation and aerodynamic forces, a force/torque sensor with 6 components was used to test the corresponding aerodynamic forces. Experimental results indicated that the flexible deformations demonstrate apparent cyclic features, in accordance with the flapping cyclic movements. The deformations in spanwise and chordwise are coupled together; a change of chordwise rib stiffness can cause more change in spanwise deformation. A certain lag in phase was observed between the deformation and the flapping movements. This was because the deformation was caused by both the aerodynamic force and the inertial force. The stiffness had a significant effect on the deformation, which in turn, affected the aerodynamic and power characteristics. In the scope of this study, the wing with medium stiffness consumed the least power. The purpose of this research is to explore some fundamental characteristics, as well as the experimental setup is described in detail, which is helpful to understand the basic aerodynamic characteristics of flapping wings. The results of this study can provide an inspiration to further understand and design flapping-wing micro air vehicles with better performance.

Effects of Different Forms of Extrinsic Feedback on the Accuracy of Force Production and to Differentiate this Force in the Simple Cyclic Movements of the Upper and Lower Limb

Background: This study aimed to assess the accuracy of force production by the limbs and to identify the ability to differentiate this force during a progressively increasing value, in response to different types of extrinsic feedback. Material and methods: The study involved nineteen healthy and physically active boys and girls aged 12.82±0.34 years, body height 157.05±9.02 cm, and body mass 44.89±7.89 kg. The tasks were to perform a series of right and left upper limb pulls and pushes with increasing force using the levers of the kinesthesiometer and a series of lower limb presses on the pedal of the kinesthesiometer. The tasks were completed in three feedback conditions: no feedback, sound feedback, verbal feedback, and the retention test was used. To assess the level of accuracy of force production, the novel index of force production accuracy (FPAIndex) was used. Results: The outcomes expressing the value of FPAIndex on the point scale indicated that the highest level of kinesthetic differentiation was observed when no feedback was provided (1.17 points), and the lowest kinesthetic differentiation was recorded when verbal feedback was provided (3.33 points). However, they were devoid of statistical value. The repeated-measures analysis of variance ANOVA with the Tukey post-hoc test (HSD) indicated a significant lowest (p=0.0402) level of accuracy of FPA (x̄ 36.12±18.29 [N]) only for the act of left lower limb press (LL PRESS) in the retention test, while no feedback was provided to the subjects. Conclusions: The results of this study showed that verbal and sound extrinsic feedback did not affect the accuracy of force production by the upper and lower limbs and the ability to differentiate this force in simple movements among children.

Fully automated algorithm estimates muscle fascicle length from ultrasound image

While ultrasound is a useful tool for visualizing muscle in vivo, traditional analysis involves substantial manual labor. Semi-automated algorithms have been introduced in recent years, reducing the amount of time required for extracting pennation angles and fascicle lengths from ultrasound images. Unfortunately, semi-automated algorithms still require some user actions and thereby subjective decision making. We here present a freely available, fully automated feature detection algorithm that involves Hessian filtering to highlight line-like objects within the ultrasound image. Hough transform is used to determine muscle fascicle angles and feature detection is used to determine the location and angle of aponeuroses. As a demonstration, we test the algorithm on ultrasound images obtained from vastus lateralis muscle in healthy individuals (N = 9) during isometric knee extension moment production (0 – 45 N-m) at three knee angles (15-25 deg). Pennation angle, muscle thickness and fascicle length vary with knee moment and knee angle in line with previous observations. Specifically, fascicle length decreases with larger knee moments and increases towards knee flexion. We expect the proposed algorithm to be useful for estimating muscle fascicle lengths during cyclic movements like human locomotion.

Running a Marathon—Its Influence on Achilles Tendon Structure

Context Several studies have been conducted to better understand the effect of load on the Achilles tendon structure. However, the effect of a high cumulative load consisting of repetitive cyclic movements, such as those that occur during the running of a marathon, on Achilles tendon structure is not yet clear. Clinicians, coaches, and athletes will benefit from knowledge about the effects of a marathon on the structure of the Achilles tendon. Objective To investigate the short-term response of the Achilles tendon structure to running a marathon. Design Case series (prospective). Setting Sports medicine centers. Patients or Other Participants Ten male nonelite runners who ran in a marathon. Main Outcomes Measure(s) Tendon structure was assessed before and 2 and 7 days after a marathon using ultrasound tissue characterization (UTC), an imaging tool that quantifies tendon organization in 4 echo types (I–IV). Echo type I represents the most stable echo pattern, and echo type IV, the least stable. Results At 7 days postmarathon, both the insertional and midportion structure changed significantly. At both sites, the percentage of echo type II increased (insertion P &lt; .01; midportion P = .02) and the percentages of echo types III and IV decreased (type III: insertion P = .01; midportion P = .02; type IV: insertion P = .01; midportion P &lt; .01). Additionally, at the insertion, the percentage of echo type I decreased (P &lt; .01). Conclusions We observed the effects of running a marathon on the Achilles tendon structure 7 days after the event. Running the marathon combined with the activity performed shortly thereafter might have caused the changes in tendon structure. This result emphasizes the importance of sufficient recovery time after running a marathon to prevent overuse injuries.

Mechanotherapy as a methods of physical therapy in people with traumatic damage to the peripheral nerves of the upper limb

The article highlights the use of mechanotherapy in traumatic injuries of the peripheral nerves of the upper limb. Damage to the nerves of the upper extremities is one of the frequent and severe types of injuries that can dramatically change the quality and lifestyle of a person, both in everyday household and professional environments. The classification of simulators and mechanotherapeutic devices that are advisable to use for traumatic neuropathies of the upper limb, the principles of motor rehabilitation. It is noted that mechanotherapy can be used to facilitate the execution of any movement (robotic mechanotherapy) and with the goal of training with increasing intensity, aimed at strengthening the motor, cardiovascular and respiratory systems (active mechanotherapy). The characteristic of the main robotic devices that are used to train hand function with the presence of feedback and the use of a gaming or virtual environment is given. It is noted that the modern direction of training rehabilitation is robotic mechanotherapy, the basis of which is the use of robotic devices for training hand function with the presence of feedback and the use of a game or virtual environment.The advantage of robot therapy is a higher quality of training compared to classical mechanotherapy due to the greater accuracy of repetitive cyclic movements, a constant training program, the availability of tools to assess the success of the classes with the possibility of demonstration to the patient. Robotic devices in rehabilitation treatment of the upper limb include MITMANUS, ARM Trainer, mirror-image motion enable (MIME) robot, Armeo, etc. The authors draws attention to the fact that training on modern simulators and devices in no way replace traditional means of physical therapy and should be used in conjunction with other rehabilitation measures in neurological patients.

CHANGES IN THE FUNCTIONAL STATUS IN CHILDREN WITH CEREBRAL PALSY WHEN PERFORMING CYCLIC MOVEMENTS

Aim. The article aims at improving functional activity in children with cerebral palsy based on the features of adaptation to cyclic motions. Materials and methods. 23 children with cerebral palsy aged from 2 to 14 years participated in the study regardless of the form of disease. Functional shifts were assessed under the effect of cyclic load on the cardiovascular system. The following methods were used for the study: heart rate variability analysis based on the changes in total power spectrum (TPw, mc2), relative values of heart rate spectrum characteristics (HF%, LF%, VLF%), and the Stress Index (SI). Results. It was established that long-term hyponesia affected negatively hemodynamics in children with cerebral palsy and contributed to a decrease in adaptation mechanisms. The initial functional status of children with cerebral palsy was characterized by low values of adaptation reserves, aerobic power, and recovery potential. Adaptive capabilities in children when growing up from 3 to 12 years decrease to asthenization. Conclusion. Motor performance is the most effective factor influencing improvement of functional capabilities in children with cerebral capabilities. The movements of the cyclic type contribute to an increase in excitability and muscle lability, as well as to the development of general endurance.